The disclosure of Japanese Patent Application No. 2000-255831 filed on Aug. 25, 2000 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
1. Field of Invention
The invention relates to a parking brake system for a vehicle, such as an automotive vehicle, which is arranged to selectively apply and remove a parking brake to and from wheels of the vehicle by operating an electrically operated actuator, and more particularly to such a vehicle parking brake system having a function of automatically applying or removing the parking brake by controlling the electrically operated actuator depending upon an operating condition of the vehicle. This invention is also concerned with a method of controlling such a vehicle parking brake system.
2. Description of Related Art
An example of the vehicle parking brake system of the type described above is disclosed in JP-B2-3-2696. This vehicle parking brake system has an automatic mode in which a parking brake is automatically applied and removed to and from the vehicle, and a manual mode in which the parking brake is applied and removed by manual operations by the vehicle operator. The automatic and manual modes are selectively established. In the automatic mode, the parking brake is automatically applied to the vehicle when a predetermined condition is satisfied, for instance, when a brake pedal is in operation while the vehicle is stationary, and the parking brake application is automatically released when a predetermined condition is satisfied, for instance, when an accelerator pedal is operated while the vehicle is stationary. In the manual mode, the parking brake is selectively applied to or removed from the vehicle, in response to an manual operation of a manually operable member. The parking brake system disclosed in the publication identified above is further arranged such that the manually operable member permits application of the parking brake to the vehicle even while the vehicle is running. However, this parking brake application during the vehicle running is possible only where a service brake system (a normal braking system) becomes defective.
In the parking brake system described above, the parking brake is applied and removed to and from the vehicle by operating the manually operable member even in the automatic mode. This parking brake system is basically arranged such that the operation in the automatic mode and the operation in the manual mode are performed independently of each other, except where the service brake system is defective. That is, the manual operation in the automatic mode is effective only once for that manual operation. However after the parking brake application and release by the manual operation are canceled, the subsequent parking brake application and release are effected in the automatic mode depending upon whether the predetermined conditions indicated above are satisfied or not. In this respect, it is noted that the parking brake mechanism may freeze if the vehicle, braked by the parking brake system in the automatic mode, is parked for a long time during cold weather. To prevent this freezing, it is desired to remove the parking brake from the vehicle by operating the manually operable member, even in the automatic mode. After the manual operation of the manually operable member, however, the parking brake is again automatically applied to the vehicle in the automatic mode. To prevent this parking brake application in the automatic mode, it is necessary to first switch the operating mode of the parking brake system from the automatic mode to the manual mode, and then operate the manually operable member for removing the parking brake. When it is desired to establish the automatic mode again, the manual mode must be changed to the automatic mode, again. Thus, the known parking brake system does not permit parking brake application and removal as desired in the manual mode, while assuring ease of control of the system in the automatic mode.
If the service brake system becomes defective, the above-mentioned parking brake system can apply the parking brake by the manual operation while the vehicle is running. That is, the manual operation can be performed only when the defect of the service brake system is detected. However if the defect of the service brake system is not detected, the parking brake system can not brake the vehicle by the manual operation in a case where the operator of the vehicle can not brake the vehicle for some physical defect of the operator and so on, or a case where the operator does not desire braking the vehicle by the service brake.
The invention thus provides a parking brake system and a method of the parking brake system for an automotive vehicle or other vehicle, which permits parking brake application to the vehicle by operation of a manually operable member even in the automatic mode, even while the service brake system is not defective, or which permits desired manual control for parking brake application and removal, while assuring ease of control of the system in the automatic mode.
In a first exemplary aspect of the invention, the invention provides a parking brake system for a vehicle with a parking-brake-force control mechanism driven by an electrically operated actuator and which is operable to selectively apply and remove a parking brake force to and from a wheel of the vehicle; an automatic-mode selector, manually operable by an operator of the vehicle, to select an automatic mode in which the parking brake force is automatically applied and removed to and from the wheel; a manual-mode control member, manually operable by the operator, to selectively apply and remove the parking brake force to and from the wheel; a first vehicle-state detector that detects the first operating state of the vehicle; a second vehicle-state detector that detects the predetermined second operating state of the vehicle; and a controller that controls the parking-brake-force control mechanism in the automatic mode according to a first operating state of the vehicle to control automatic application and removal of the parking brake force detected by the first vehicle-state detector, controls the parking-brake-force control mechanism in response to an operation of the manual-mode control member to control manual application and removal of the parking brake force, and restricts an automatic control of the parking-brake-force control mechanism in the automatic mode until detection of a predetermined second operating state of the vehicle by the second vehicle-state detector.
In the parking brake system constructed according to the first exemplary aspect of this invention, the controller is arranged to restrict the automatic control of the parking-brake-force control mechanism by the controller until detection of the predetermined second operating state of the vehicle. Accordingly, the operation of the manual-mode control member substantially permits the parking-brake-force control mechanism to be controlled to selectively apply and remove the parking brake force to and from the wheel of the vehicle even while the automatic mode is selected. Thus, the present parking brake system permits desired manual control of the parking-brake-force control mechanism with the manual-mode control member, while assuring ease of control of the mechanism in the automatic mode.
The parking brake system constructed according to the principle of the invention is applicable to various types of vehicles including not only automotive vehicles driven by an engine and/or an electric motor, but also vehicles not equipped with a drive power source.
In a second exemplary aspect of the invention, the invention provides A method of controlling a parking brake system for a vehicle, the parking brake system comprising: (a) a parking-brake-force control mechanism driven by an electrically operated actuator and which is operable to selectively apply and remove a parking brake force to and from a wheel of the vehicle; (b) an automatic-mode selector, manually operable by an operator of the vehicle, to select an automatic mode in which the parking brake force is automatically applied and removed to and from the wheel; (c) a manual-mode control member, manually operable by the operator, to selectively apply and remove the parking brake force to and from the wheel; and (d) a controller that controls the parking-brake-force control mechanism according to a first operating state of the vehicle to control automatic application and removal of the parking brake force, and controls the parking-brake-force control mechanism, to control manual application and removal of the parking brake force, the method comprises the steps of: detecting operation of the manual-mode control member; removing the operation of the manual-mode control upon detection of a predetermined second operating state of the vehicle; and restricting an automatic control of the parking-brake-force control mechanism while the manual-mode control member is operated.
According to the method of the invention described above, the automatic control of the parking-brake-force control mechanism by the controller is restricted while the manual-mode control member is operated. Accordingly, the operation of the manual-mode control member substantially permits the parking-brake-force control mechanism to be controlled to selectively apply and remove the parking brake force to and from the wheel of the vehicle even while the automatic mode is selected. Thus, the present parking brake system permits desired manual control of the parking-brake-force control mechanism with the manual-mode control member, while assuring ease of control of the mechanism in the automatic mode.
In a third exemplary aspect of the invention, the invention provides a parking brake system for a vehicle with a parking-brake-force control mechanism driven by an electrically operated actuator and which is operable to selectively apply and remove a parking brake force to and from a wheel of the vehicle; a manual-mode control member, manually operable by the operator, to effect at least one of application and removal of the parking brake force to and from the wheel; and a controller that controls the parking-brake-force control mechanism according to an operating state of the vehicle to control automatic application and removal of the parking brake force, to control the parking-brake-force control mechanism in response to an operation of the manual-mode control member to control the at least one of application and removal of the parking brake force to and from the wheel, and control restricts an automatic control of the parking-brake-force control mechanism during the operation of the manual-mode control member.
The parking brake system constructed according to the third exemplary aspect of this invention is simplified in construction owing to the elimination of a manually operable automatic-mode selector as provided in the parking brake system constructed according to the first aspect of the invention.
In a fourth exemplary aspect of the invention, the invention provides a method of controlling a parking brake system for a vehicle, the parking brake system comprises: (a) a parking-brake-force control mechanism driven by an electrically operated actuator and which is operable to selectively apply and remove a parking brake force to and from a wheel of the vehicle; (b) a manual-mode control member, manually operable by the operator, to effect at least one of application and removal of the parking brake force to and from the wheel; and (c) a controller that controls the parking-brake-force control mechanism according to an operating state of the vehicle to control automatic application and removal of the parking brake force, and to control the parking-brake-force control mechanism in response to an operation of the manual-mode control member to control the at least one of application and removal of the parking brake force to and from the wheel, the method comprising the steps of: detecting an operation of the manual-mode control; and restricting an automatic control of the parking-brake-force control mechanism by the controller during the operation of the manual-mode control member.